Prevention of aortic and cardiac fibrosis by spironolactone in old normotensive rats

Cellular elasticity in cancer: a review of altered biomechanical features

A large number of studies have shown that changes in biomechanical characteristics are an important indicator of tumor transformation in normal cells. Elastic deformation is one of the more studied biomechanical features of tumor cells, which plays an important role in tumourigenesis and development. Altered cell elasticity often brings many indications. This manuscript reviews the effects of altered cellular elasticity on cell characteristics, including adhesion viscosity, migration, proliferation, and differentiation elasticity and stiffness. Also, the physical factors that may affect cell elasticity, such as temperature, cell height, cell-viscosity, and aging, are summarized. Then, the effects of cell-matrix, cytoskeleton, in vitro culture medium, and cell-substrate with different three-dimensional structures on cell elasticity during cell tumorigenesis are outlined. Importantly, we summarize the current signaling pathways that may affect cellular elasticity, as well as tests for cellular elastic deformation. Finally, we summarize current hybrid materials: polymer-polymer, protein-protein, and protein-polymer hybrids, also, nano-delivery strategies that target cellular resilience and cases that are at least in clinical phase 1 trials. Overall, the behavior of cancer cell elasticity is modulated by biological, chemical, and physical changes, which in turn have the potential to alter cellular elasticity, and this may be an encouraging prediction for the future discovery of cancer therapies.

Hypertension in chronic kidney disease: What lies behind the scene

Hypertension is a frequent condition encountered during kidney disease development and a leading cause in its progression. Hallmark factors contributing to hypertension constitute a complexity of events that progress chronic kidney disease (CKD) into end-stage renal disease (ESRD). Multiple crosstalk mechanisms are involved in sustaining the inevitable high blood pressure (BP) state in CKD, and these play an important role in the pathogenesis of increased cardiovascular (CV) events associated with CKD. The present review discusses relevant contributory mechanisms underpinning the promotion of hypertension and their consequent eventuation to renal damage and CV disease. In particular, salt and volume expansion, sympathetic nervous system (SNS) hyperactivity, upregulated renin–angiotensin–aldosterone system (RAAS), oxidative stress, vascular remodeling, endothelial dysfunction, and a range of mediators and signaling molecules which are thought to play a role in this concert of events are emphasized. As the control of high BP via therapeutic interventions can represent the key strategy to not only reduce BP but also the CV burden in kidney disease, evidence for major strategic pathways that can alleviate the progression of hypertensive kidney disease are highlighted. This review provides a particular focus on the impact of RAAS antagonists, renal nerve denervation, baroreflex stimulation, and other modalities affecting BP in the context of CKD, to provide interesting perspectives on the management of hypertensive nephropathy and associated CV comorbidities.

Mineralocorticoid receptor antagonist treatment of established pulmonary arterial hypertension improves interventricular dependence in the SU5416-hypoxia rat model

Treatment with mineralocorticoid receptor (MR) antagonists beginning at the outset of disease, or early thereafter, prevents pulmonary vascular remodeling in preclinical models of pulmonary arterial hypertension (PAH). However, the efficacy of MR blockade in established disease, a more clinically relevant condition, remains unknown. Therefore, we investigated the effectiveness of two MR antagonists, eplerenone (EPL) and spironolactone (SPL), after the development of severe right ventricular (RV) dysfunction in the rat SU5416-hypoxia (SuHx) PAH model. Cardiac magnetic resonance imaging (MRI) in SuHx rats at the end of week 5, before study treatment, confirmed features of established disease including reduced RV ejection fraction and RV hypertrophy, pronounced septal flattening with impaired left ventricular filling and reduced cardiac index. Five weeks of treatment with either EPL or SPL improved left ventricular filling and prevented the further decline in cardiac index compared with placebo. Interventricular septal displacement was reduced by EPL whereas SPL effects were similar, but not significant. Although MR antagonists did not significantly reduce pulmonary artery pressure or vessel remodeling in SuHx rats with established disease, animals with higher drug levels had lower pulmonary pressures. Consistent with effects on cardiac function, EPL treatment tended to suppress MR and proinflammatory gene induction in the RV. In conclusion, MR antagonist treatment led to modest, but consistent beneficial effects on interventricular dependence after the onset of significant RV dysfunction in the SuHx PAH model. These results suggest that measures of RV structure and/or function may be useful endpoints in clinical trials of MR antagonists in patients with PAH.

Atrial Fibrillation and Aortic Ectasia as Complications of Primary Aldosteronism: Focus on Pathophysiological Aspects

Primary aldosteronism (PA) is the most common cause of secondary hypertension. A growing body of evidence has suggested that, beyond its well-known effects on blood pressure and electrolyte balance, aldosterone excess can exert pro-inflammatory, pro-oxidant and pro-fibrotic effects on the kidney, blood vessels and heart, leading to potentially harmful pathophysiological consequences. In clinical studies, PA has been associated with an increased risk of cardiovascular, cerebrovascular, renal and metabolic complication compared to essential hypertension, including atrial fibrillation (AF) and aortic ectasia. An increased prevalence of AF in patients with PA has been demonstrated in several clinical studies. Aldosterone excess seems to be involved in the pathogenesis of AF by inducing cardiac structural and electrical remodeling that in turn predisposes to arrhythmogenicity. The association between PA and aortic ectasia is less established, but several studies have demonstrated an effect of aldosterone on aortic stiffness, vascular smooth muscle cells and media composition that, in turn, might lead to an increased risk of aortic dilation and dissection. In this review, we focus on the current evidence regarding the potential role of aldosterone excess in the pathogenesis of AF and aortic ectasia.

CCN2 (Cellular Communication Network Factor 2) Deletion Alters Vascular Integrity and Function Predisposing to Aneurysm Formation

Background:

CCN2 (cellular communication network factor 2) is a matricellular protein involved in cell communication and microenvironmental signaling responses. CCN2 is known to be overexpressed in several cardiovascular diseases, but its role is not completely understood.

Methods:

Here, CCN2 involvement in aortic wall homeostasis and response to vascular injury was investigated in inducible Ccn2 -deficient mice, with induction of vascular damage by infusion of Ang II (angiotensin II; 15 days), which is known to upregulate CCN2 expression in the aorta.

Results:

Ang II infusion in CCN2-silenced mice lead to 60% mortality within 10 days due to rapid development and rupture of aortic aneurysms, as evidenced by magnetic resonance imaging, echography, and histological examination. Ccn2 deletion decreased systolic blood pressure and caused aortic structural and functional changes, including elastin layer disruption, smooth muscle cell alterations, augmented distensibility, and increased metalloproteinase activity, which were aggravated by Ang II administration. Gene ontology analysis of RNA sequencing data identified aldosterone biosynthesis as one of the most enriched terms in CCN2-deficient aortas. Consistently, treatment with the mineralocorticoid receptor antagonist spironolactone before and during Ang II infusion reduced aneurysm formation and mortality, underscoring the importance of the aldosterone pathway in Ang II–induced aorta pathology.

Conclusions:

CCN2 is critically involved in the functional and structural homeostasis of the aorta and in maintenance of its integrity under Ang II–induced stress, at least, in part, by disruption of the aldosterone pathway. Thus, this study opens new avenues to future studies in disorders associated to vascular pathologies.

The effect of spironolactone on cardiac and renal fibrosis following myocardial infarction in established hypertension in the transgenic Cyp1a1Ren2 rat

AIMS

The renin-angiotensin-aldosterone axis plays a key role in mediating cardiac and kidney injury. Mineralocorticoid receptor antagonism has beneficial effects on cardiac dysfunction, but effects are less well quantified in the cardiorenal syndrome. This study investigated cardiac and kidney pathophysiology following permanent surgical ligation to induce myocardial infarction (MI) in hypertensive animals with or without mineralocorticoid receptor antagonism.

METHODS

Hypertension was induced in adult male Cyp1a1Ren2 rats. Hypertensive animals underwent MI surgery (n = 6), and were then treated daily with spironolactone for 28 days with serial systolic blood pressure measurements, echocardiograms and collection of urine and serum biochemical data. They were compared to hypertensive animals (n = 4), hypertensive animals treated with spironolactone (n = 4), and hypertensive plus MI without spironolactone (n = 6). Cardiac and kidney tissue was examined for histological and immunohistochemical analysis.

RESULTS

MI superimposed on hypertension resulted in an increase in interstitial cardiac fibrosis (p<0.001), renal cortical interstitial fibrosis (p<0.01) and glomerulosclerosis (p<0.01). Increased fibrosis was accompanied by myofibroblast and macrophage infiltration in the heart and the kidney. Spironolactone post-MI, diminished the progressive fibrosis (p<0.001) and inflammation (myofibroblasts (p<0.05); macrophages (p<0.01)) in both the heart and the kidney, despite persistently elevated SBP (182±19 mmHg). Despite the reduction in inflammation and fibrosis, spironolactone did not modify ejection fraction, proteinuria, or renal function when compared to untreated animals post MI.

CONCLUSION

This model of progressive cardiorenal dysfunction more closely replicates the clinical setting. Mineralocorticoid receptor blockade at a clinically relevant dose, blunted progression of cardiac and kidney fibrosis with reduction in cardiac and kidney inflammatory myofibroblast and macrophage infiltration. Further studies are underway to investigate the combined actions of angiotensin blockade with mineralocorticoid receptor blockade.

The Pathogenesis of COVID-19 Myocardial Injury: An Immunohistochemical Study of Postmortem Biopsies

Rationale

Myocardial injury associates significantly and independently with mortality in COVID-19 patients. However, the pathogenesis of myocardial injury in COVID-19 remains unclear, and cardiac involvement by SARS-CoV-2 presents a major challenge worldwide.

Objective

This histological and immunohistochemical study sought to clarify the pathogenesis and propose a mechanism with pathways involved in COVID-19 myocardial injury.

Methods and Results

Postmortem minimally invasive autopsies were performed in six patients who died from COVID-19, and the myocardium samples were compared to a control group (n=11). Histological analysis was performed using hematoxylin-eosin and toluidine blue staining. Immunohistochemical (IHC) staining was performed using monoclonal antibodies against targets: caspase-1, caspase-9, gasdermin-d, ICAM-1, IL-1β, IL-4, IL-6, CD163, TNF-α, TGF-β, MMP-9, type 1 and type 3 collagen. The samples were also assessed for apoptotic cells by TUNEL. Histological analysis showed severe pericardiocyte interstitial edema and higher mast cells counts per high-power field in all COVID-19 myocardium samples. The IHC analysis showed increased expression of caspase-1, ICAM-1, IL-1β, IL-6, MMP-9, TNF-α, and other markers in the hearts of COVID-19 patients. Expression of caspase-9 did not differ from the controls, while gasdermin-d expression was less. The TUNEL assay was positive in all the COVID-19 samples supporting endothelial apoptosis.

Conclusions

The pathogenesis of COVID-19 myocardial injury does not seem to relate to primary myocardiocyte involvement but to local inflammation with associated interstitial edema. We found heightened TGF-β and interstitial collagen expression in COVID-affected hearts, a potential harbinger of chronic myocardial fibrosis. These results suggest a need for continued clinical surveillance of patients for myocardial dysfunction and arrythmias after recovery from the acute phase of COVID-19.

Plasma Biomarker Profiling in Heart Failure Patients with Preserved Ejection Fraction before and after Spironolactone Treatment: Results from the Aldo-DHF Trial

The pathophysiology of heart failure with preserved ejection fraction (HFpEF) is poorly understood and therapeutic strategies are lacking. This study aimed to identify plasma proteins with pathophysiological relevance in HFpEF and with respect to spironolactone-induced effects. We assessed 92 biomarkers in plasma samples from 386 HFpEF patients—belonging to the Aldo-DHF trial—before (baseline, BL) and after one-year treatment (follow up, FU) with spironolactone (verum) or a placebo. At BL, various biomarkers showed significant associations with the two Aldo-DHF primary end point parameters: 33 with E/e’ and 20 with peak VO₂. Ten proteins including adrenomedullin, FGF23 and inflammatory peptides (e.g., TNFRSF11A, TRAILR2) were significantly associated with both parameters, suggesting a role in the clinical HFpEF presentation. For 13 proteins, expression changes from BL to FU were significantly different between verum and placebo. Among them were renin, growth hormone, adrenomedullin and inflammatory proteins (e.g., TNFRSF11A, IL18 and IL4RA), indicating distinct spironolactone-mediated effects. BL levels of five proteins, e.g., inflammatory markers such as CCL17, IL4RA and IL1ra, showed significantly different effects on the instantaneous risk for hospitalization between verum and placebo. This study identified plasma proteins with different implications in HFpEF and following spironolactone treatment. Future studies need to define their precise mechanistic involvement.

The Dose-Dependent Effects of Spironolactone on TGF-β1 Expression and the Vulnerability to Atrial Fibrillation in Spontaneously Hypertensive Rats

OBJECTIVE

This study tends to assess the dose-dependent effects of spironolactone on TGF-β1 expression, atrial fibrosis, and the vulnerability to atrial fibrillation in spontaneously hypertensive rats (SHRs) and tries to clarify the association of atrial fibrosis with the vulnerability to atrial fibrillation.

METHODS

Forty 20-week-old male SHRs were randomly divided into 4 groups (10 rats per group): 3 spironolactone groups were lower-dose group (10 mg·kg-1·d-1, dissolved in 2 ml saline solution, group SL), medium-dose group (40 mg·kg-1·d-1, dissolved in 2 ml saline solution, group SM), higher-dose group (80 mg·kg-1·d-1, dissolved in 2 ml saline solution, group SH) and one hypertension group (2 ml saline solution for stomach gavage, group H). Ten matched homologous WKY rats were set as the control group (group C). After 7 weeks of gavage, a multiple electroconductive physiological recorder was used to detect atrial electrical parameters, including P-wave duration, PR interval, and atrial effective refractory period (AERP), the inducibility, and duration of atrial fibrillation. HE staining was used to determine myocardial cell size. Masson staining was used to detect the deposition of the interstitial collagen fibers in atrial muscle. The expression of TGF-β1 was detected by immunohistochemistry and western blot.

RESULTS

Compared with group C, the myocardial cell size, atrial fibrosis, TGF-β1 expression, P-wave duration, PR interval, AERP, inducibility, and duration of atrial fibrillation in group H were conspicuously increased (p < 0.05); compared with group H, there was no significant difference in the myocardial cell size, atrial fibrosis, TGF-β1 expression, and electrophysiological indexes in group SH upon spironolactone intervention (p > 0.05); compared with group H, the myocardial cell size, atrial fibrosis, the expression of TGF-β1, P-wave duration, PR interval, the inducibility, and duration of atrial fibrillation in the group SL and group SM were all decreased (p < 0.05); compared with group SM, the effect in the group SL was more prominent (p < 0.01).

CONCLUSION

Hypertension can lead to cardiomyocyte hypertrophy, deposition of interstitial fibrosis in myocardial tissue, and an increase in the vulnerability to atrial fibrillation. Spironolactone showed a certain dose-dependent effect in SHRs. Lower-dose spironolactone was superior to higher-dose spironolactone in the aspect of reducing hypertensive atrial fibrosis and TGF-β1 expression, as well as preventing the occurrence of atrial fibrillation.

Spironolactone Reduces Aortic Stiffness in Patients With Resistant Hypertension Independent of Blood Pressure Change

Background

Aortic stiffness is an independent predictor of cardiovascular events in patients with arterial hypertension. Resistant hypertension is often linked to hyperaldosteronism and associated with adverse outcomes. Spironolactone, a mineralocorticoid receptor antagonist, has been shown to reduce both the arterial blood pressure (BP) and aortic stiffness in resistant hypertension. However, the mechanism of aortic stiffness reduction by spironolactone is not well understood. We hypothesized that spironolactone reduces aortic stiffness in resistant hypertension independently of BP change.

Methods and Results

Patients with uncontrolled BP (≥140/90 mm Hg) despite use of ≥3 antihypertensive medications (including diuretics) were prospectively recruited. Participants were started on spironolactone at 25 mg/d, and increased to 50 mg/d at 4 weeks while other antihypertensive medications were withdrawn to maintain constant mean BP. Phase‐contrast cardiac magnetic resonance imaging of the ascending aorta was performed in 30 participants at baseline and after 6 months of spironolactone treatment to measure aortic pulsatility, distensibility, and pulse wave velocity. Pulse wave velocity decreased (6.3±2.3 m/s to 4.5±1.8 m/s, P<0.001) and pulsatility and distensibility increased (15.9%±5.3% to 22.1%±7.9%, P<0.001; and 0.28%±0.10%/mm Hg to 0.40%±0.14%/mm Hg, P<0.001, respectively) following 6 months of spironolactone.

Conclusions

Our results suggest that spironolactone improves aortic properties in resistant hypertension independently of BP, which may support the hypothesis of an effect of aldosterone on the arterial wall. A larger prospective study is needed to confirm our findings.

Association of long-term SBP with clinical outcomes and quality of life in heart failure with preserved ejection fraction: an analysis of the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist trial

AIMS

To determine the associations of long-term SBP (LT-SBP) levels with clinical outcomes and health-related quality of life in heart failure with preserved ejection fraction (HFpEF).

METHODS AND RESULTS

We analyzed participants from the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist (TOPCAT) study with available different SBP measurements from different follow-ups (n = 3310). LT-SBP was the mean SBP value from 4-week measurement to the last one. The outcome measures are all-cause mortality and a composite of heart failure readmission or all-cause mortality and the Kansas City Cardiomyopathy Questionnaire (KCCQ) overall summary score. To determine the associations of LT-SBP and outcomes, we used adjusted Cox proportional hazards models and restricted cubic spline models. After multivariable adjustment, LT-SBP of 120-129 and 130-139 mmHg were associated with a lower risk of mortality (hazard ratio 0.66, 95% CI 0.51-0.87, P = 0.003; hazard ratio 0.68, 95% CI 0.51-0.90, P = 0.007, respectively); LT-SBP of 100-119 mmHg had similar risk of mortality (hazard ratio 0.96, 95% CI 0.72-1.28, P = 0.778) compared with LT-SBP of at least 140 mmHg. There was U-shaped relationship between LT-SBP and all-cause mortality (P < 0.001) with nadir risk occurring around 123 mmHg. Similar relationships were observed between LT-SBP and composite end point of heart failure readmission or all-cause mortality. The adjusted mean improvement in KCCQ score was significantly higher in the 120-129 mmHg group than in the at least 140 mmHg group beginning from the 12-month follow-up visit without significant differences in other groups.

CONCLUSION

Among patients with HFpEF, long-term control of SBP level at 120-129 mmHg is independently associated with the highest risk reduction of all-cause mortality and improvement of KCCQ score. Future randomized clinical trials need to specifically evaluate optimal SBP treatment goals in patients with HFpEF.

Prognostic impact of mineralocorticoid receptor antagonist in patients with heart failure with preserved ejection fraction

AIMS

This study aims to investigate the prognostic impact of mineralocorticoid receptor antagonists (MRAs) on cardiovascular events in patients hospitalized for acute decompensated heart failure with preserved ejection fraction (HFpEF; defined as left ventricular ejection fraction ≥45%).

METHODS AND RESULTS

A prospective multicentre cohort study was conducted in Nagano prefecture, Japan, between July 2014 and December 2018 that contained 518 consecutive HFpEF patients hospitalized for acute decompensated heart failure (HF). The primary outcome was a composite of cardiovascular death and HF readmission. We compared the incidence of cardiovascular events between patients who were prescribed with MRAs and those who were not in a propensity score matched cohort using a Cox proportional hazards regression model with a propensity score derived from 23 baseline variables. For sensitivity analysis, we conducted Cox proportional hazards regression models for the primary outcome adjusting for 16 clinically relevant variables in the crude cohort. The median age was 83 years, and 53% were female. The median left ventricular ejection fraction was 61%. During a median follow-up of 553 days, the primary outcome occurred in 192 (37%) patients. MRAs were used in 255 (49%) patients. After analysis, a matched cohort consisting of 370 patients was created. After propensity score matching, the baseline characteristics were well balanced between the two groups. The incidence of the primary outcome was significantly lower in MRA users than in non-users [32% (59/185) vs. 49% (90/185); hazard ratio (HR) 0.669, 95% confidence interval (CI) 0.482-0.929, P = 0.016]. The incidence of cardiovascular death was also significantly lower in the MRA users [11% (21/185) vs. 22% (41/185); HR, 0.563; 95% CI, 0.333-0.953; P = 0.032]. The risk of HF readmission tended to be lower in the MRA users [29% (54/185) vs. 41% (75/185); HR, 0.738; 95% CI, 0.520-1.048; P = 0.089]. MRA use was also associated with a lower risk of the primary outcome after Cox proportional hazards analysis adjusting for 16 clinically relevant variables in the crude cohort (HR, 0.710; 95% CI 0.507-0.995; P = 0.047).

CONCLUSIONS

Mineralocorticoid receptor antagonist use was significantly associated with a lower risk of the primary composite outcome of cardiovascular death and HF readmission in patients hospitalized for acute decompensated HFpEF. The incidence of cardiovascular mortality was also significantly lower in these patients.

Cardiac tissue remodeling in healthy aging: the road to pathology

This review aims to highlight the normal physiological remodeling that occurs in healthy aging hearts, including changes that occur in contractility, conduction, valve function, large and small coronary vessels, and the extracellular matrix. These "normal" age-related changes serve as the foundation that supports decreased plasticity and limited ability for tissue remodeling during pathophysiological states such as myocardial ischemia and heart failure. This review will identify populations at greater risk for poor tissue remodeling in advanced age along with present and future therapeutic strategies that may ameliorate dysfunctional tissue remodeling in aging hearts.

Spironolactone mitigates, but does not reverse, the progression of renal fibrosis in a transgenic hypertensive rat

Hypertension plays an important role in the development and progression of chronic kidney disease. Studies to date, with mineralocorticoid receptor antagonists (MRA), have demonstrated varying degrees of results in modifying the development of renal fibrosis. This study aimed to investigate whether treatment with a MRA commenced following the establishment of hypertension, a situation more accurately representing the clinical setting, modified the progression of renal fibrosis. Using male Cyp1a1Ren2 rats (n = 28), hypertension was established by addition of 0.167% indole-3-carbinol (w/w) to the rat chow, for 2 weeks prior to treatment. Rats were then divided into normotensive, hypertensive (H), or hypertensive with daily oral spironolactone treatment (H + SP) (human equivalent dose 50 mg/day). Physiological data and tissue were collected after 4 and 12 weeks for analysis. After 4 weeks, spironolactone had no demonstrable effect on systolic blood pressure (SBP), proteinuria, or macrophage infiltration in the renal cortex. However, glomerulosclerosis and renal cortical fibrosis were significantly decreased. Following 12 weeks of spironolactone treatment, SBP was lowered (not back to normotensive levels), proteinuria was reduced, and the progression of glomerulosclerosis and renal cortical fibrosis was significantly blunted. This was associated with a significant reduction in macrophage and myofibroblast infiltration, as well as CTGF and pSMAD2 expression. In summary, in a model of established hypertension, spironolactone significantly blunted the progression of renal fibrosis and glomerulosclerosis, and downregulated the renal inflammatory response, which was associated with reduced proteinuria, despite only a partial reduction in systolic blood pressure. This suggests a blood pressure independent effect of MRA on renal fibrosis.

Microvascular Dysfunction in Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is an increasingly studied entity accounting for 50% of all diagnosed heart failure and that has claimed its own dignity being markedly different from heart failure with reduced EF in terms of etiology and natural history (Graziani et al., 2018). Recently, a growing body of evidence points the finger toward microvascular dysfunction as the major determinant of the pathological cascade that justifies clinical manifestations (Crea et al., 2017). The high burden of comorbidities such as metabolic syndrome, hypertension, atrial fibrillation, chronic kidney disease, obstructive sleep apnea, and similar, could lead to a systemic inflammatory state that impacts the physiology of the endothelium and the perivascular environment, engaging complex molecular pathways that ultimately converge to myocardial fibrosis, stiffening, and dysfunction (Paulus and Tschope, 2013). These changes could even self-perpetrate with a positive feedback where hypoxia and locally released inflammatory cytokines trigger interstitial fibrosis and hypertrophy (Ohanyan et al., 2018). Identifying microvascular dysfunction both as the cause and the maintenance mechanism of this condition has opened the field to explore specific pharmacological targets like nitric oxide (NO) pathway, sarcomeric titin, transforming growth factor beta (TGF-β) pathway, immunomodulators or adenosine receptors, trying to tackle the endothelial impairment that lies in the background of this syndrome (Graziani et al., 2018;Lam et al., 2018). Yet, many questions remain, and the new data collected still lack a translation to improved treatment strategies. To further elaborate on this tangled and exponentially growing topic, we will review the evidence favoring a microvasculature-driven etiology of this condition, its clinical correlations, the proposed diagnostic workup, and the available/hypothesized therapeutic options to address microvascular dysfunction in the failing heart.

PKCδ Mediates Mineralocorticoid Receptor Activation by Angiotensin II to Modulate Smooth Muscle Cell Function

Angiotensin II (AngII) and the mineralocorticoid receptor (MR) ligand aldosterone both contribute to cardiovascular disorders, including hypertension and adverse vascular remodeling. We previously demonstrated that AngII activates MR-mediated gene transcription in human vascular smooth muscle cells (SMCs), yet the mechanism and the impact on SMC function are unknown. Using an MR-responsive element-driven transcriptional reporter assay, we confirm that AngII induces MR transcriptional activity in vascular SMCs and endothelial cells, but not in Cos1 or human embryonic kidney-293 cells. AngII activation of MR was blocked by the MR antagonist spironolactone or eplerenone and the protein kinase C-δ (PKCδ) inhibitor rottlerin, implicating both in the mechanism. Similarly, small interfering RNA knockdown of PKCδ in SMCs prevented AngII-mediated MR activation, whereas knocking down of MR blocked both aldosterone- and AngII-induced MR function. Coimmunoprecipitation studies reveal that endogenous MR and PKCδ form a complex in SMCs that is enhanced by AngII treatment in association with increased serine phosphorylation of the MR N terminus. AngII increased mRNA expression of the SMC-MR target gene, FKBP51, via an MR-responsive element in intron 5 of the FKBP51 gene. The impact of AngII on FKBP51 reporter activity and gene expression in SMCs was inhibited by spironolactone and rottlerin. Finally, the AngII-induced increase in SMC number was also blocked by the MR antagonist spironolactone and the PKCδ inhibitor rottlerin. These data demonstrate that AngII activates MR transcriptional regulatory activity, target gene regulation, and SMC proliferation in a PKCδ-dependent manner. This new mechanism may contribute to synergy between MR and AngII in driving SMC dysfunction and to the cardiovascular benefits of MR and AngII receptor blockade in humans.

Myocardial global longitudinal strain: An early indicator of cardiac interstitial fibrosis modified by spironolactone, in a unique hypertensive rat model

OBJECTIVES

Is global longitudinal strain (GLS) a more accurate non-invasive measure of histological myocardial fibrosis than left ventricular ejection fraction (LVEF) in a hypertensive rodent model.

BACKGROUND

Hypertension results in left ventricular hypertrophy and cardiac dysfunction. Speckle-tracking echocardiography has emerged as a robust technique to evaluate cardiac function in humans compared with standard echocardiography. However, its use in animal studies is less clearly defined.

METHODS

Cyp1a1Ren2 transgenic rats were randomly assigned to three groups; normotensive, untreated hypertensive or hypertensive with daily administration of spironolactone (human equivalent dose of 50 mg/day). Cardiac function and interstitial fibrosis development were monitored for three months.

RESULTS

The lower limit of normal LVEF was calculated to be 75%. After three months hypertensive animals (196±21 mmHg systolic blood pressure (SBP)) showed increased cardiac fibrosis (8.8±3.2% compared with 2.4±0.7% % in normals), reduced LVEF (from 81±2% to 67±7%) and impaired myocardial GLS (from -17±2% to -11±2) (all p<0.001). Myocardial GLS demonstrated a stronger correlation with cardiac interstitial fibrosis (r2 = 0.58, p<0.0001) than LVEF (r2 = 0.37, p<0.006). Spironolactone significantly blunted SBP elevation (184±15, p<0.01), slowed the progression of cardiac fibrosis (4.9±1.4%, p<0.001), reduced the decline in LVEF (72±4%, p<0.05) and the degree of impaired myocardial GLS (-13±1%, p<0.01) compared to hypertensive animals.

CONCLUSIONS

This study has demonstrated that, myocardial GLS is a more accurate non-invasive measure of histological myocardial fibrosis compared to standard echocardiography, in an animal model of both treated and untreated hypertension. Spironolactone blunted the progression of cardiac fibrosis and deterioration of myocardial GLS.

Aldosterone stimulation mediates cardiac metabolism remodeling via Sirt1/AMPK signaling in canine model

Aldosterone (Aldo), a pivotal hormone that is ubiquitously expressed in systemic tissues of mammals, is a crucial factor in the pathogenesis of cardiac disease. Accumulating evidence suggests that disturbances in cell energy metabolism are involved in increasing aldosterone levels. However, the precise mechanism underlying the impact of cardiac metabolic remodeling underlying aldosterone stimulation remains limited. In this work, we evaluated the underlying effect of aldosterone on regulating cardiac metabolism remodeling in a canine model. Fifteen beagle dogs were divided into a control group (n = 5), Aldo group (n = 5), and a group treated with spironolactone (SP), a mineralocorticoid receptor antagonist (n = 5), for 4 weeks. Blood pressure, electrocardiogram and respiratory parameters, H&E, Masson staining, ultrastructural changes, the adenosine triphosphate (ATP) and free fatty acid (FFA) levels of ventricular tissues, the level of mRNA, and the protein expression of key metabolic factors and regulators were assessed. The Sirt1/AMPK signaling pathway was significantly inhibited in the canine model of aldosterone stimulation, resulting in a reduction of the key downstream metabolic factors involved in glucose and fatty acid oxidation. The dysregulation of expression of key factors in glycogen metabolism led to glycogen deposition, an increase in FFA levels, a reduction in ATP levels, apoptosis, inflammatory cell infiltration, and mitochondrial damage in the ventricular myocardium. These effects were significantly restored by spironolactone. Aldosterone stimulation induced cardiac metabolic remodeling in ventricular cardiomyocytes possibly through the Sirt1/AMPK signaling pathway, implying that this pathway may provide a novel therapeutic target for cardiac metabolic remodeling.

Usefulness of myocardial work measurement in the assessment of left ventricular systolic reserve response to spironolactone in heart failure with preserved ejection fraction

Aims

Improvement in left ventricular (LV) systolic reserve, including exertional increase in global longitudinal strain (GLS), may contribute to the clinical benefit from therapeutic interventions in heart failure with preserved ejection fraction (HFpEF). However, GLS is an afterload-dependent parameter, and its measurements may not adequately reflect myocardial contractility recruitment with exercise. The estimation of myocardial work (MW) allows correction of GLS for changing afterload. We sought to investigate the associations of GLS and MW parameters with the response of exercise capacity to spironolactone in HFpEF.

Methods and results

We analysed 114 patients (67 ± 8 years) participating in the STRUCTURE study (57 randomized to spironolactone and 57 to placebo). Resting and immediately post-exercise echocardiograms were performed at baseline and at 6-month follow-up. The following indices of MW were assessed: global work index (GWI), global constructive work (GCW), global wasted work, and global work efficiency. The amelioration of exercise intolerance at follow-up in the spironolactone group was accompanied by a significant improvement in exertional increase in GCW (P = 0.002) but not in GLS and other MW parameters. Increase in exercise capacity at 6 months was independently correlated with change in exertional increase in GCW from baseline to follow-up (β = 0.24; P = 0.009) but not with GLS (P = 0.14); however, no significant interaction with the use of spironolactone on peak VO2 was found (P = 0.97).

Conclusion

GCW as a measure of LV contractile response to exertion is a better determinant of exercise capacity in HFpEF than GLS. Improvement in functional capacity during follow-up is associated with improvement in exertional increment of GCW.

Role of Aldosterone and Mineralocorticoid Receptor in Cardiovascular Aging

The mineralocorticoid receptor (MR) was originally identified as a regulator of blood pressure, able to modulate renal sodium handling in response to its principal ligand aldosterone. MR is expressed in several extra-renal tissues, including the heart, vasculature, and adipose tissue. More recent studies have shown that extra-renal MR plays a relevant role in the control of cardiovascular and metabolic functions and has recently been implicated in the pathophysiology of aging. MR activation promotes vasoconstriction and acts as a potent pro-fibrotic agent in cardiovascular remodeling. Aging is associated with increased arterial stiffness and vascular tone, and modifications of arterial structure and function are responsible for these alterations. MR activation contributes to increase blood pressure with aging by regulating myogenic tone, vasoconstriction, and vascular oxidative stress. Importantly, aging represents an important contributor to the increased prevalence of cardiometabolic syndrome. In the elderly, dysregulation of MR signaling is associated with hypertension, obesity, and diabetes, representing an important cause of increased cardiovascular risk. Clinical use of MR antagonists is limited by the adverse effects induced by MR blockade in the kidney, raising the risk of hyperkalaemia in older patients with reduced renal function. Therefore, there is an unmet need for the enhanced understanding of the role of MR in aging and for development of novel specific MR antagonists in the context of cardiovascular rehabilitation in the elderly, in order to reduce relevant side effects.

Role of spironolactone in the treatment of heart failure with preserved ejection fraction

Heart failure (HF) is the leading cause of morbidity and mortality globally. Heart failure with preserved ejection fraction (HFpEF) is currently responsible for about half of the patients affected with HF and is associated with impaired functional capacity, as well as significant morbidity due to frequent hospitalizations. Unfortunately, despite its poor prognosis, the management of HFpEF is very controversial and no therapy has been so far shown to reduce mortality in HFpEF. Spironolactone antagonizes the effect of aldosterone and can lead to a reduction in fibrosis and an improvement in left ventricular (LV) function. Furthermore, spironolactone decreases extracellular matrix turnover and myocardial collagen content and improves endothelial vasomotor dysfunction, mechanisms known to influence the progression of HF. Thus, given the aforementioned beneficial actions of spironolactone, extensive research has been conducted to explore the effects of spironolactone on HFpEF. Our review aims to present and discuss the clinical and scientific data pertaining to the role of spironolactone in the treatment of patients with HFpEF.

Vascular compliance in women with polycystic ovary syndrome treated with spironolactone

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age in the United States and has been associated with several diseases including cardiovascular disease, obesity, and glucose intolerance. In this study, systolic blood pressure, diastolic blood pressure, pulse pressure (vascular compliance), large artery elasticity, systemic vascular resistance (SVR), total vascular impedance (TVI), and body mass index (BMI) were measured before and after treatment with spironolactone in 10 women with PCOS. Systolic BP, diastolic BP, and BMI were similar prior to treatment and after treatment. Pulse pressure decreased slightly post-treatment compared to pretreatment but not to significance (P = 0.07). The results show that after treatment with spironolactone, there was a statistically significant increase in large artery elasticity (P = 0.047), while there was a statistically significant decrease in SVR and TVI (P = 0.0005 and P = 0.03). This study indicates that treatment with spironolactone improves large artery elasticity and reduces systemic vascular resistance without any change in small artery elasticity.

Sympathetic drive stimulating diastolic dysfunction?

Diastolic heart failure accounts for half of the heart failure population and its pathophysiology remains an area of active research. The renin angiotensin and aldosterone axis has been the focus of clinical trials to treat patients with heart failure with preserved ejection fraction, however with limited yield in terms of clinical success. Sympathetic activity has been considered a plausible cause for the molecular changes that lead to diastolic dysfunction. Based on this understanding the study by Gimelli et al uses MIBG to evaluate for association between diastolic dysfunction and sympathetic denervation. The results of this study set the stage for a follow up study for evaluation of sympathetic denervation in isolated diastolic dysfunction.

Biomarker-based phenotyping of myocardial fibrosis identifies patients with heart failure with preserved ejection fraction resistant to the beneficial effects of spironolactone: results from the Aldo-DHF trial

BACKGROUND

Myocardial fibrosis is characterized by excessive cross-linking and deposition of collagen type I and is involved in left ventricular stiffening and left ventricular diastolic dysfunction (LVDD). We investigated whether the effect of spironolactone on LVDD in patients with heart failure with preserved ejection fraction (HFpEF) depends on its effects on collagen cross-linking and/or deposition.

METHODS AND RESULTS

We investigated 381 HFpEF patients from the multicentre, randomized, placebo-controlled Aldo-DHF trial with measures of the E:e' ratio. The ratio of serum carboxy-terminal telopeptide of collagen type I to serum matrix metalloproteinase-1 (CITP:MMP-1, an inverse index of myocardial collagen cross-linking) and serum carboxy-terminal propeptide of procollagen type I (PICP, a direct index of myocardial collagen deposition) were determined at baseline and after 1-year treatment with spironolactone 25 mg once daily or placebo. Patients were classified by CITP:MMP-1 and PICP tertiles at baseline. While CITP:MMP-1 tertiles at baseline interacted (P < 0.05) with spironolactone effect on E:e', PICP tertiles did not. In fact, while spironolactone treatment did not modify E:e' in patients with lower CITP:MMP-1 levels, this ratio was significantly reduced in the remaining spironolactone-treated patients. In addition, PICP was unchanged in patients with lower CITP:MMP-1 levels but was reduced in the remaining spironolactone-treated patients.

CONCLUSIONS

A biochemical phenotype of high collagen cross-linking identifies HFpEF patients resistant to the beneficial effects of spironolactone on LVDD. It is suggested that excessive collagen cross-linking, which stabilizes collagen type I fibres, diminishes the ability of spironolactone to reduce collagen deposition in these patients.

Smooth Muscle Cell-Mineralocorticoid Receptor as a Mediator of Cardiovascular Stiffness With Aging

Stiffening of the vasculature with aging is a strong predictor of adverse cardiovascular events, independent of all other risk factors including blood pressure, yet no therapies target this process. MRs (mineralocorticoid receptors) in smooth muscle cells (SMCs) have been implicated in the regulation of vascular fibrosis but have not been explored in vascular aging. Comparing SMC-MR-deleted male mice to MR-intact littermates at 3, 12, and 18 months of age, we demonstrated that aging-associated vascular stiffening and fibrosis are mitigated by MR deletion in SMCs. Progression of cardiac stiffness and fibrosis and the decline in exercise capacity with aging were also mitigated by MR deletion in SMC. Vascular gene expression profiling analysis revealed that MR deletion in SMC is associated with recruitment of a distinct antifibrotic vascular gene expression program with aging. Moreover, long-term pharmacological inhibition of MR in aged mice prevented the progression of vascular fibrosis and stiffness and induced a similar antifibrotic vascular gene program. Finally, in a small trial in elderly male humans, short-term MR antagonism produced an antifibrotic signature of circulating biomarkers similar to that observed in the vasculature of SMC-MR-deleted mice. These findings suggest that SMC-MR contributes to vascular stiffening with aging and is a potential therapeutic target to prevent the progression of aging-associated vascular fibrosis and stiffness.

Arterial (Aortic) Stiffness in Patients with Resistant Hypertension: from Assessment to Treatment

PURPOSE OF REVIEW

The purpose of the review is to examine whether measurement of aortic stiffness could be especially value-adding for risk stratification and treatment among patients with resistant hypertension (RH).

RECENT FINDINGS

Adverse arterial remodeling and increased aortic stiffness is associated with RH, and it may be of additional clinical benefit to measure aortic stiffness in these patients. However, there is insufficient evidence to determine whether aortic stiffness is excessively high relative to the level of blood pressure (BP) among people with RH. This issue needs resolution as it could help refine management decisions guided by aortic stiffness. If conventional antihypertensive therapy fails to lower BP in patients with RH, there is good rationale for effectiveness of spironolactone as add on therapy, and this should also improve aortic stiffness. Lifestyle intervention with exercise and diet should be additionally efficacious towards improving BP and aortic stiffness in patients with RH, but there is limited data in this patient population. For better characterization on the effects of BP treatment on aortic stiffness, measures of central aortic BP may help refine management decisions above and beyond conventional arm cuff BP. There is strong evidence to support the use of aortic stiffness as a tool to aid risk stratification in hypertension management. Although there is a theoretical basis for special additional benefit of measuring aortic stiffness in patients with RH (as distinct from uncomplicated hypertension), at this time, there is inadequate data available to make definitive conclusions and is an area for future investigation.

Differences in left ventricular functional adaptation to arterial stiffness and neurohormonal activation in patients with hypertension: a study with two-dimensional layer-specific speckle tracking echocardiography

Background

Arterial stiffness increases pressure load to the left ventricle (LV), leading to LV hypertrophy and subendocardial ischemia. Neurohormones stimulate myocardial fibrosis and LV dysfunction. We aimed to explore the associations of arterial stiffness and plasma aldosterone with multi-directional, layer-specific LV, and left atrial (LA) mechanical function in hypertensive patients.

Methods

Layer-specific LV global longitudinal strain (GLS-trans, GLS-endo, GLS-epi), global circumferential strain (GCS-trans, GCS-endo, GCS-epi), LV torsional parameters, and LA global longitudinal strain (LA GLS) were analyzed by two-dimensional speckle tracking echocardiography in 195 hypertensive patients (110 men, mean age 55 years). Pulse wave velocity (PWV) was analyzed as a measure of arterial stiffness, and plasma aldosterone was measured for evaluation of neurohormonal activation.

Results

In a simple correlation, PWV significantly correlated with LV GLS-endo and LA GLS. Log aldosterone correlated with both LV GCS-endo and LV GCS-trans. Multiple regression analysis revealed that LV GLS-endo (β = 0.223, p = 0.031) and LA GLS (β = −0.311, p = 0.002) were independently correlated with PWV even after controlling for confounding factors.

Conclusions

In hypertensive patients without clinically apparent target organ damage, LV GLS, especially endocardium, and LA GLS were more dominantly affected by arterial stiffness because, among the three myocardial layers, the endocardium is most susceptible to pressure overload. Two-dimensional layer-specific speckle-tracking echocardiography sensitively detects LV mechanical dysfunction and provides pathophysiologic insights into LV mechanical adaptations in hypertension.

Hypertensive Cardiovascular Risk: Pulsatile Hemodynamics, Gender, and Therapeutic Implications

PURPOSE

In recent years, the predictive value of 2 pulsatile parameters has been extensively studied in hypertension: aortic stiffness and pulse pressure (PP) amplification. Aortic stiffness is an index of aortic rigidity and PP-amplification is the ratio between central and brachial PP, an indirect evaluation of wave reflections. Both are safe, independent, noninvasive predictors of overall and cardiovascular risk. Our purpose is to determine the validity of these parameters in 2 different circumstances: gender and therapeutic implications.

AGE EFFECT

Studies have shown that whereas steady mean arterial pressure is significantly higher in men than in women, pulsatile pressure largely predominates in women, mostly in older age and as a consequence of short stature. Gender differences require more extensive investigation due to the disparities of dose-response ranging among populations and the contribution of ethnic factors, frequently based on individual origin.

REGARDING THERAPEUTIC IMPLICATIONS

Many questions have yet to be resolved. First, the prognosis of antihypertensive therapy is largely based on blood pressure reduction but also requires evaluation of arterial rigidity and wave reflections to achieve adequate therapeutic "de-stiffening." The most effective approach appears to be the combination of angiotensin- and calcium-channel blockade, in certain cases associated with diuretic compounds. Second, antialdosterone drugs can be useful, but it is their antifibrotic more than their antihypertensive effect that appears effective. Third, prevention of comorbidities, such as those associating hypertension, diabetes, and/or kidney damage, should become primary targets for drug treatment.

Toward a broader understanding of aldosterone in congestive heart failure

Discovered some 50 years ago, aldosterone (ALDO) has come to be recognised as a mineralocorticoid hormone with well-known endocrine properties in epithelial cells that contribute to the pathophysiology of congestive heart failure. This includes Na + resorption at the expense of K+ excretion in classic target tissues: kidneys, colon, sweat and salivary glands. Though less well known, Mg2+ excretion is likewise enhanced by ALDO, while adrenal ALDO secretion is regulated by extracellular Mg2+ ([Mg2+ ]o). An emerging body of information has and continues to identify other endocrine actions of ALDO receptor-ligand binding. They include: promoting an efflux of cytosolic free Mg2+, or [Mg2+]i, in exchange for Na+ in such non-epithelial cells as peripheral blood mononuclear cells; its influence on endothelial cell function; and its central actions that involve regulation of cerebrospinal fluid composition produced by epithelial cells of the choroid plexus, activity of the hypothalamic paraventricular nucleus involved in Na+ appetite, Na+ and H2O excretion and sympathetic nerve activity, and the regulation of TNF-α production from central and/or peripheral sources. Extra-adrenal steroidogenesi and auto/paracrine properties of ALDO generated de novo in the cardiovasculature are now under investigation and preliminary findings suggest they contribute to tissue repair. The past decade has witnessed a revival of interest in this steroid molecule. In years to come, an even broader understanding of ALDO's contribution to the pathophysiology of congestive heart failure will undoubtedly emerge.

Differences Between Cardiac and Arterial Fibrosis and Stiffness in Aldosterone-Salt Rats: Effect of Eplerenone

Background. Previous experiments have studied separately the development of either cardiac or aortic fibrosis and stiffness in aldosterone (Aldo)-salt hypertensive rats. Our aim was to determine in vivo the effects of Aldo and the Aldo receptor antagonist eplerenone (Epl) on simultaneous changes in cardiac and arterial structure and function and their interactions.

Methods and Results. Aldo was administered in uninephrectomised Sprague-Dawley rats receiving a high-salt diet from 8 to 12 weeks of age. Three groups of Aldo-salt rats were treated with 1 to 100 mg/kg-1. d-1 Epl by gavage. Arterial elasticity was measured by elastic modulus (Einc)-wall stress curves using medial cross-sectional area (MCSA). The cardiac and arterial walls were analysed by histomorphometry (elastin and collagen), immunohistochemistry (EIIIA fibronectin, Fn), and Northern blot (collagens I and III). Aldo caused increased systolic blood pressure (SBP), carotid Einc, MCSA, and EIIIA Fn with no change in wall stress or elastin and collagen densities. No difference in collagen mRNA levels was detected between groups. During the same period, cardiac mass and collagen mRNA and protein levels increased markedly in the myocardial tissue. Epl normalised collagen in the myocardium, Eincwall stress curves, MCSA, and EIIIA Fn in Aldo rats. These dose-dependent effects were not accompanied by a consistent reduction in SBP and cardiac mass.

Conclusions. In exogenous hyperaldosteronism in the rat, Aldo causes independently myocardial collagen and arterial Fn accumulation, the latter being responsible for increased intrinsic carotid stiffness. Epl prevents both cardiac and arterial effects but does not reduce consistently SBP.

Beneficial Cardiovascular Actions of Eplerenone in the Spontaneously Hypertensive Rat

Background: Aldosterone has been implicated as a potential mediator of cardiac and vascular damage in a variety of disorders. This study examined the role of aldosterone and its interplay with the renin-angiotensin system in the pathogenesis of hypertension. To this end, the effects of the aldosterone antagonist eplerenone and the angiotensin converting enzyme inhibitor lisinopril on cardiovascular mass, myocardial collagen, and coronary circulation were examined in spontaneously hypertensive rats.

Methods: Male, 22-week-old rats were randomly divided into 4 groups (12 in each). The control group received no treatment, the second group was given eplerenone (100 mg/kg/day), the third received lisinopril (3 mg/kg/day), and the fourth was given eplerenone and lisinopril. After 12 weeks of respective treatments, systemic and regional hemodynamics and cardiovascular mass indexes were measured in conscious instrumented rats.

Results: Eplerenone decreased arterial pressure but did not affect left ventricular mass or hydroxyproline concentration (an estimate of collagen). It did, however, reduce minimal coronary vascular resistance and increased coronary flow reserve. Lisinopril decreased arterial pressure and ventricular mass but did not affect regional hemodynamics. The combination therapy produced synergistic effects.

Conclusion: Aldosterone antagonism improved coronary and systemic hemodynamics in adult spontaneously hypertensive rats but did not affect cardiovascular mass indexes. The finding that lisinopril and eplerenone decreased arterial pressure to the same extent but had different cardiovascular effects suggested that these effects might be pressure independent.

Stem cell therapy restores viscoelastic properties of myocardium in rat model of hypertension

Extensive remodeling of the myocardium is seen in a variety of cardiovascular diseases, including systemic hypertension. Stem cell therapy has been proposed to improve the clinical outcomes of hypertension, and we hypothesized that changes in mechanical properties of the myocardium would accompany the progression of disease and the results of treatment conditions. Using spontaneously hypertensive rats (SHR) as a model of hypertension, we treated 13-week-old hypertensive rats with a single injection of adipose-derived stem cells (ADSC) isolated from a normotensive control. We indented the isolated ventricles of control, untreated sham-injected SHR, and ADSC-treated SHR hearts with a custom cantilever-based system and fit the resulting data to a standard linear solid model. SHR animals had higher blood pressure (198.4±25.9mmHg) and lower ejection fraction (69.9±4.2%) than age-matched control animals (109.0±1.6mmHg, 88.2±1.3%), and increased viscoelastic properties accompanied these clinical changes (right ventricle effective stiffness, SHR: 21.97±5.10kPa, Control: 13.14±3.48kPa). ADSC-treated animals saw improvement in clinical parameters compared to the untreated SHR group, which was also accompanied by a significant restoration of viscoelastic properties of the myocardium (ACSD-treated SHR: 9.77±6.96kPa).

The effect of aldosterone-antagonist therapy on aortic elastic properties in patients with nonischemic dilated cardiomyopathy

BACKGROUND

Many studies proved the prognostic importance of aortic stiffness as an independent predictor of cardiovascular morbidity and all-cause mortality. The decrease of arterial compliance has a high prevalence in patients with heart failure and affects both hemodynamics and prognosis. Aortic stiffness is partially caused by excessive activation of the renin-angiotensin-aldosterone system. Spironolactone, a mineralcorticoid receptor antagonist (MRA), has been shown to decrease aortic stiffness and fibrosis in experimental models. However, there are few studies that describe the effects of MRA on aortic stiffness in patients with nonischemic dilated cardiomyopathy.

AIMS

To evaluate the effect of spironolactone on aortic stiffness in patients with nonischemic dilated cardiomyopathy.

MATERIALS AND METHODS

We randomized (1 : 1) 102 patients with nonischemic dilated cardiomyopathy with New York Heart Association class I-II to receive spironolactone 25 mg/day (up to 100 mg/day) or placebo, in addition to recommended therapy. Aortic stiffness index, aortic strain, aortic distensibility and aortic dimensions were assessed at baseline and after 6 months. All measures were obtained with echocardiography M-mode at 3 cm above the aortic valve on parasternal long axis view and simultaneous brachial arterial pressure with sphygmomanometer.

RESULTS

Ascending aorta diameters, aortic stiffness index, aortic distensibility and aortic strain were similar at randomization in the two groups. After 6 months of therapy in the treated group, we found a reduction of aortic stiffness index (7.2 ± 3.5 versus 9.6 ± 4.8 mmHg; P = 0.03) and an increase of aortic distensibility (3.77 ± 1.0 versus 2.92 ± 0.55 mmHg; P = 0.01) and systolic aortic strain (10.0 ± 5.0 versus 8.0% ± 2.1%; P = 0.01). There were no difference in systolic arterial pressure, diastolic arterial pressure and differential pressure in the two groups.

CONCLUSION

Therapy with spironolactone is effective in reducing aortic stiffness in patients with nonischemic dilated cardiomyopathy. This effect could improve hemodynamics supporting the use of MRAs in patients with low New York Heart Association class (I-II).

Heart Failure With Preserved Ejection Fraction: What Is in a Name?

Evidence-based management of heart failure (HF) with preserved left ventricular ejection fraction (LVEF; HFpEF) remains a major gap in the care of patients with HF. Clinical trials directed toward the population with HFpEF have been disappointing, although renin-angiotensin-aldosterone system blockade appears to prevent HF in populations predisposed to HFpEF. This paradox may partly be because of inhomogeneity within the HF populations studied. Although the term HFpEF is often used to imply a specific diagnosis, in fact this constellation may be due to a large variety of disease states with different underlying pathophysiologic mechanisms. Furthermore, in patients with HF, regardless of LVEF, myocardial dysfunction is common during both systole and diastole, and LVEF is influenced at least as much by the pattern of left ventricular remodeling as it is by myocardial contractility. The most common clinical-pathologic syndrome responsible for HFpEF is strongly associated with hypertension, with the metabolic syndrome, and with older age. Recent findings support that this condition is mediated via endothelial dysfunction, inflammation, oxidative stress, myocyte hypertrophy, and altered collagen turnover. We, therefore, propose the terms "metabolic HF" and "senile HF" to describe this specific disease state. The search for therapies designed to prevent, halt, or reverse HF should more strongly focus on populations carefully selected to represent specific underlying cardiovascular disease states.

Effect of Mineralocorticoid Receptor Antagonists on Cardiac Structure and Function in Patients With Diastolic Dysfunction and Heart Failure With Preserved Ejection Fraction: A Meta-Analysis and Systematic Review

BACKGROUND

There has been an increasing interest in use of mineralocorticoid receptor antagonists (MRAs) in patients with heart failure with preserved ejection fraction (HFPEF). However, a comprehensive evaluation of MRA effects on left ventricular (LV) structure and function in these patients is lacking. In this meta-analysis, we evaluated the effects of MRAs on LV structure and function among patients with diastolic dysfunction or HFPEF.

METHODS & RESULTS

Randomized, controlled clinical trials evaluating the efficacy of MRAs in patients with diastolic dysfunction or HFPEF were included. The primary outcome was change in E/e', a specific measure of diastolic function. Secondary outcomes included changes in other measures of diastolic function, LV structure, surrogate markers for myocardial fibrosis (carboxy-terminal peptide of procollagen type I [PICP] and amino-terminal peptide of pro-collagen type-II [PIIINP]), blood pressure, and exercise tolerance. In the pooled analysis, MRA use was associated with significant reduction in E/e' (weighted mean difference [WMD] [95% confidence interval {CI}]: -1.68 [-2.03 to -1.33]; P<0.0001) and deceleration time (WMD [95% CI]: -12.0 ms [-23.3 to -0.7]; P=0.04) as compared with control, suggesting and improvement in diastolic function. Furthermore, blood pressure and levels of PIIINP and PICP were also significantly reduced with MRA therapy with no significant change in LV mass or dimensions.

CONCLUSION

MRA therapy in patients with asymptomatic diastolic dysfunction or HFPEF is associated with significant improvement in diastolic function and markers of cardiac fibrosis without a significant change in LV mass or dimensions.

Effects of renin-angiotensin-aldosterone system inhibitors on mortality, hospitalization, and diastolic function in patients with HFpEF. A meta-analysis of 13 randomized controlled trials

AIM

The purpose of this meta-analysis was to evaluate the effects of renin-angiotensin-aldosterone system (RAAS) inhibitors on mortality, hospitalization, diastolic function, and exercise capacity in heart failure with preserved ejection fraction (HFpEF).

METHODS

Thirteen randomized controlled trials (RCTs), totaling 12,532 patients with HFpEF, were selected. All-cause and cardiovascular mortality, all-cause and heart failure-related hospitalization, diastolic function, and the 6-min walk distance were assessed. The risk ratios (RR) of the dichotomous data, weighted mean difference (WMD) of continuous data, and 95 % confidence intervals (CI) were calculated to assess the effects of RAAS inhibitors.

RESULTS

RAAS inhibitors significantly decreased heart failure-related hospitalization (RR 0.89; 95 % CI 0.82-0.97; p = 0.01) and improved the diastolic function, as reflected in a reduced E/e' index (MD -1.38; 95 % CI -2.01 to -0.74; p < 0.0001). However, there were no beneficial effects on all-cause cardiovascular mortality and all-cause hospitalization. Other diastolic parameters had few changes compared with the controls. The 6-min walk distance was not improved by the use of RAAS inhibitors.

CONCLUSION

In patients with HFpEF, RAAS inhibitors decreased heart-failure hospitalization and the E/e' index without affecting mortality, all-cause hospitalization, other diastolic function parameters, and the 6-min walk distance.

Effects of spironolactone on ventricular-arterial coupling in patients with chronic systolic heart failure and mild symptoms

BACKGROUND

Several studies demonstrated that mineralocorticoid receptor antagonists (MRAs) are able to prevent myocardial and vascular fibrosis, and left ventricular (LV) remodeling in patients with systolic chronic heart failure (HF) and mild symptoms. Ventricular-arterial coupling (VAC) should be influenced by anti-fibrotic interventions. We have assessed the effects of spironolactone on VAC and its components, aortic elastance (Ea) and end-systolic LV elastance (Ees), in patients with HF.

METHODS AND RESULTS

Changes from baseline in VAC were compared between 65 patients treated with spironolactone and 32 controls not receiving MRAs. All patients had HF, reduced LVEF with reduced LV ejection fraction (LVEF) and New York Heart Association (NYHA) functional class I-II symptoms, and underwent transthoracic echocardiography at baseline and after 6 months. VAC was estimated by the modified single-beat method as Ea/Ees. Parameters of LV function improved after 6 month treatment with spironolactone with an increase in the LVEF from 34 ± 8 to 39 ± 8 % (p < 0.001). Spironolactone increased Ees from 1.32 ± 0.38 to 1.57 ± 0.42 mmHg/mL (p < 0.001) and reduced VAC from 2.03 ± 0.59 to 1.66 ± 0.31 (p < 0.001), but did not affect Ea and V0 (LV volume at end-systolic pressure of 0 mmHg). No change in any of these parameters occurred in the control group.

CONCLUSIONS

6-month therapy with spironolactone improved VAC mainly through its effect on Ees in patients with mild HF.

Can antihypertensive medication interfere with the vicious cycle between hypertension and vascular calcification?

Vascular calcification is a phenomenon of disturbed calcium deposition, as part of the calcium that is supposed to be deposited to our bones, is lodged to our vessels. There are two forms of vascular calcification, each with a distinct anatomical distribution and clinical relevance, namely the intimal and medial calcification. Studies have demonstrated that hypertension may cause vascular calcification but also that both types of calcification, especially medial, promote arterial rigidity and hence hypertension. Implications of this two-way road are largely unknown as there is no consensus yet on their exact clinical value. However, several antihypertensive medications seem to be able to interfere with the cycle of high blood pressure and vascular calcium deposits. The present review summarizes the up-to-date data regarding the effect of antihypertensive medication on vascular calcification.

Management strategies for heart failure with preserved ejection fraction

The management of heart failure with preserved ejection fraction (HFpEF) is challenging and requires an accurate diagnosis. Although currently there is no convincing therapy that prolongs survival in patients with HFpEF, treatment of fluid retention and of comorbidities, such as hypertension, myocardial ischemia, and atrial fibrillation, may improve symptoms and quality of life. Future outcome trials testing the efficacy of promising new agents will have better characterization of patient phenotype to maximize the potential response to therapies. This article provides current management strategies available for HFpEF, gives an overview of previous trials that have failed to prove the benefit of therapies to improve outcomes, and highlights promising novel therapies.

Endothelial sodium channels trigger endothelial salt sensitivity with aging

The epithelial sodium channel is also expressed in vascular endothelium (endothelial sodium channel [EnNaC]). Depending on ambient sodium concentration, EnNaC is associated with mechanical stiffening of the endothelial cell cortex, leading to endothelial dysfunction. Because the incidence of both salt sensitivity and endothelial dysfunction increases with age, we investigated the abundance of EnNaC in aging mice. To assess EnNaC functionality and endothelial salt sensitivity, stiffness was measured while ambient sodium was varied. Aortae of young (3 months) and old (15 months) C57BL/6J wild-type mice were kept ex vivo on a physiological concentration of aldosterone (0.45 nmol/L). Spironolactone (10 nmol/L) and amiloride (1 μmol/L) were applied for aldosterone antagonism and EnNaC blockage, respectively. EnNaC at the endothelial cell surface was quantified by immunofluorescence staining. Cortical stiffness was monitored by atomic force microscopy when ambient sodium was raised from 135 to 150 mmol/L. In ex vivo aortae of older mice, endothelial cells had significantly higher EnNaC numbers than those of younger mice (+23%). In parallel, cortical stiffness was found increased (+8.5%). Acute application of high sodium led to an immediate rise in stiffness in both groups but was pronounced in endothelium of older mice (+18% versus +26%). Spironolactone and amiloride lowered EnNaC abundance and prevented endothelial stiffening under all conditions. We conclude that EnNaC mediates endothelial salt sensitivity in the aging process. This mechanism might contribute to the development of age-related cardiovascular disease and suggests the usage of spironolactone and amiloride specifically in the elderly.

Mineralocorticoid receptor antagonist in heart failure: Past, present and future perspectives

Aldosterone is involved in various deleterious effects on the cardiovascular system, including sodium and fluid retention, myocardial fibrosis, vascular stiffening, endothelial dysfunction, catecholamine release and stimulation of cardiac arrhythmias. Therefore, aldosterone receptor blockade may have several potential benefits in patients with cardiovascular disease. Mineralocorticoid receptor antagonists (MRAs) have been shown to prevent many of the maladaptive effects of aldosterone, in particular among patients with heart failure (HF). Randomized controlled trials have demonstrated efficacy of MRA in heart failure with reduced ejection fraction, both in patients with NYHA functional classes III and IV and in asymptomatic and mildly symptomatic patients (NYHA classes I and II). Recent data in patients with heart failure with preserved ejection fraction are encouraging. MRA could also have anti-arrhythmic effects on atrial and ventricular arrhythmias and may be helpful in patient ischemic heart disease through prevention of myocardial fibrosis and vascular damage. This article aims to discuss the pathophysiological effects of aldosterone in patients with cardiovascular disease and to review the current data that support the use of MRA in heart failure.

Mineralocorticoid receptors in vascular disease: connecting molecular pathways to clinical implications

The mineralocorticoid receptor (MR), a steroid-hormone-activated transcription factor, plays a substantial role in cardiovascular diseases. MR antagonists (MRAs) have long been appreciated as effective treatments for heart failure and hypertension; however, recent research suggests that additional patient populations may also benefit from MRA therapy. Experimental evidence demonstrates that in addition to its classic role in the regulating sodium handling in the kidney, functional MR is expressed in the blood vessels and contributes to hypertension, vascular inflammation and remodeling, and atherogenesis. MR activation drives pathological phenotypes in smooth muscle cells, endothelial cells, and inflammatory cells, whereas MRAs inhibit these effects. Collectively, these studies demonstrate a new role for extrarenal MR in cardiovascular disease. This review summarizes these new lines of evidence and how they contribute to the mechanisms of atherosclerosis, pulmonary and systemic hypertension, and vein graft failure, and describes new patient populations that may benefit from MRA therapy.

Long-term application of the aldosterone antagonist spironolactone prevents stiff endothelial cell syndrome

Aldosterone triggers the stiff endothelial cell syndrome (SECS), characterized by an up-regulation of epithelial sodium channels (ENaCs) and mechanical stiffening of the endothelial cell cortex accompanied by endothelial dysfunction. In vivo, aldosterone antagonism exerts sustained protection on the cardiovascular system. To illuminate the molecular mechanisms of this time-dependent effect, a study on endothelial cells in vitro and ex vivo was designed to investigate SECS over time. Endothelia (from human umbilical veins, bovine aortae, and explants of human arteries) were cultured in aldosterone-supplemented medium with or without the mineralocorticoid receptor (MR) antagonist spironolactone. MR expression, ENaC expression, cortical stiffness, and shear-mediated nitric oxide (NO) release were determined after 3 d (short term) and up to 24 d (long term). Over time, MR expression increased by 129%. ENaC expression and surface abundance increased by 32% and 42% (13.8 to 19.6 molecules per cell surface), paralleled by a 49% rise in stiffness. Spironolactone prevented this development and, after 3 wk of treatment, increased NO release by 50%. Thus, spironolactone improves endothelial function long-lastingly by preventing a time-dependent manifestation of SECS. This emphasizes the key role of vascular endothelium as a therapeutical target in cardiovascular disorders and might explain blood pressure independent actions of MR antagonism.

Smooth muscle cell mineralocorticoid receptors: role in vascular function and contribution to cardiovascular disease

The mineralocorticoid receptor (MR), a member of the steroid receptor family, regulates blood pressure by mediating the effects of the hormone aldosterone on renal sodium handling. In recent years, it has become clear that MR is expressed in vascular smooth muscle cells (SMCs), and interest has grown in understanding the direct role of SMC MR in regulating vascular function. This interest stems from multiple clinical studies where MR inhibitor treatment reduced the incidence of cardiovascular events and mortality. This review summarizes the most recent advances in our understanding of SMC MR in regulating normal vascular function and in promoting vascular disease. Many new studies suggest a role for SMC MR activation in stimulating vascular contraction and contributing to vessel inflammation, fibrosis, and remodeling. These detrimental vascular effects of MR activation appear to be independent of changes in blood pressure and are synergistic with the presence of endothelial dysfunction or damage. Thus, in humans with underlying cardiovascular disease or cardiovascular risk factors, SMC MR activation may promote hypertension, atherosclerosis, and vascular aging. Further exploration of the molecular mechanisms for the effects of SMC MR activation has the potential to identify novel therapeutic targets to prevent or treat common cardiovascular disorders.

Temporal analysis of vascular smooth muscle cell elasticity and adhesion reveals oscillation waveforms that differ with aging

A spectral analysis approach was developed for detailed study of time-resolved, dynamic changes in vascular smooth muscle cell (VSMC) elasticity and adhesion to identify differences in VSMC from young and aged monkeys. Atomic force microscopy (AFM) was used to measure Young's modulus of elasticity and adhesion as assessed by fibronectin (FN) or anti-beta 1 integrin interaction with the VSMC surface. Measurements demonstrated that VSMC cells from old vs. young monkeys had increased elasticity (21.6 kPa vs. 3.5 kPa or a 612% increase in elastic modulus) and adhesion (86 pN vs. 43 pN or a 200% increase in unbinding force). Spectral analysis identified three major frequency components in the temporal oscillation patterns for elasticity (ranging from 1.7 × 10(-3) to 1.9 × 10(-2) Hz in old and 8.4 × 10(-4) to 1.5 × 10(-2) Hz in young) and showed that the amplitude of oscillation was larger (P < 0.05) in old than in young at all frequencies. It was also observed that patterns of oscillation in the adhesion data were similar to the elasticity waveforms. Cell stiffness was reduced and the oscillations were inhibited by treatment with cytochalasin D, ML7 or blebbistatin indicating the involvement of actin-myosin-driven processes. In conclusion, these data demonstrate the efficacy of time-resolved analysis of AFM cell elasticity and adhesion measurements and that it provides a uniquely sensitive method to detect real-time functional differences in biomechanical and adhesive properties of cells. The oscillatory behavior suggests that mechanisms governing elasticity and adhesion are coupled and affected differentially during aging, which may link these events to changes in vascular stiffness.

Differential effects of late-life initiation of low-dose enalapril and losartan on diastolic function in senescent Fischer 344 x Brown Norway male rats

No proven pharmacological therapies to delay or reverse age-related diastolic dysfunction exist. We hypothesized that late-life low-dose (non-blood-pressure-lowering) angiotensin-converting enzyme inhibition vs. angiotensin II receptor blockade would be equally efficacious at mitigating diastolic dysfunction in the senescent Fischer 344 × Brown Norway rat. Enalapril (10 mg/kg/day; n = 9) initiated at 24 months of age and continued for 6 months, increased myocardial relaxation (e'), reduced Doppler-derived indices of filling pressure (E/e'), favorably lowered the ratio of phospholamban-SERCA2 and reduced oxidative stress markers, Rac1 and nitrotyrosine, in aged hearts. Treatment with losartan (15 mg/kg/day; n = 9) similarly mitigated signs of cardiac oxidative stress, but impairments in diastolic function persisted when compared with untreated rats (n = 7). Our findings favor the idea that the lusitropic benefit of low-dose angiotensin-converting enzyme inhibitor initiated late in life may be related to an antioxidant-mediated modulation of SERCA2, resulting in improved relaxation rather than via overt effects on cardiac structure or blood pressure.